1. Field of the Invention
The present invention relates to a drying jig, a drying method of a honeycomb molded body, and a manufacturing method of a honeycomb structured body.
2. Discussion of the Background
Recently, it becomes a problem that particulates such as soot, contained in exhaust gas emitted from internal combustion engines for vehicles such as a bus, a truck and the like, construction equipment and the like, do harm to the environment or the human health.
In order to solve this problem, there are proposed various filters using a honeycomb structured body made of porous ceramic as a filter for collecting particulates in exhaust gas and purifying the exhaust gas.
When a honeycomb structured body is manufactured by a conventional manufacturing method, first, a wet mixture is prepared by mixing, for example, two kinds of inorganic powders having different average particle diameters, a binder, a dispersion medium and the like. Then, this wet mixture is further mixed using a screw mixer or the like, and furthermore, the mixture was continuously extrusion-molded with a die. A molded body thus extruded is cut to a predetermined length to prepare a rectangular pillar-shaped honeycomb molded body.
Next, the obtained honeycomb molded body in a wet state is dried by use of microwave drying or hot air drying to manufacture a dried body of a honeycomb molded body which has certain strength and is easily handled.
After this drying process, by sealing an end of the specified cell, a cell of the honeycomb molded body is processed into a state in which either its ends is sealed with the plug material layer. Thereafter, the honeycomb molded body is degreased at the temperature of at least about 400° C. and at most about 650° C. in an oxygen-containing atmosphere to volatilize a solvent in organic binder components and decompose/dissipate resin components. Further, the honeycomb molded body is fired at the temperature of at least about 2000° C. and at most about 2200° C. in an inert gas atmosphere to manufacture a honeycomb fired body.
Then, by applying a sealing material paste to the side of the honeycomb fired body and bonding the honeycomb fired bodies to one another, an aggregated body of the honeycomb fired bodies in a state in which a large number of honeycomb fired bodies are bound to one another through a sealing material layer (adhesive layer) is prepared. Next, a honeycomb block is formed by cutting the obtained aggregated body of the honeycomb fired bodies into a predetermined shape such as a cylindrical pillar, a cylindroid and the like using a cutting machine and the like. Finally, a sealing material layer (coat layer) is formed by applying a sealing material paste to the periphery of the honeycomb block to complete the manufacturing of a honeycomb structured body.
In such a manufacturing method of the honeycomb structured body, a process in which drying treatment is applied to the honeycomb molded body prepared by extrusion molding, is required. Conventionally, a wet honeycomb molded body was sent in a dryer of a predetermined temperature and dried for a predetermined period of time and then taken out of the dryer.
JP-A 2001-130973 discloses a drying method of a ceramic molded body in which a drying jig comprising an upper jig and a lower jig, provided with means for applying pressure, is used and the ceramic molded body is surrounded in an adhered state from above and below with this drying jig and the ceramic molded body is dried while applying pressure thereto.
Further, JP-A 2001-130973 describes that in a process for drying a ceramic molded body, the overall ceramic molded body can be uniformly and rapidly dried without causing deformation such as warpage and the like in the ceramic molded body.
The contents of JP-A 2001-130973 are incorporated herein by reference in their entirety.